如何在R语言中为db-RDA三元图的样点设置不同颜色？

核心修改思路 #

将样点填充色bg参数从固定值，替换为与env$site（即site_names）分类对应的颜色向量即可，具体步骤如下：

1. 定义与site对应的颜色映射 #

先确认site_names的类别，创建匹配的颜色向量：

# 查看site的类别（确保是分类变量）
unique(site_names)
# 定义颜色，按site类别顺序对应，可自行替换成你需要的颜色
site_colors <- c("steelblue", "darkorange")

2. 修改points函数的bg参数 #

把原本固定的bg = "steelblue"替换为根据site_names匹配的颜色：

# 将site_names转为因子，确保颜色与类别对应正确
site_factor <- as.factor(site_names)

# 绘制分色样点
points(sc_si,
       pch = 21, 
       col = "black", 
       bg = site_colors[site_factor],  # 按site类别映射颜色
       cex = 1.2)

3. 添加图例（可选但推荐） #

为了让图形更清晰，添加图例说明颜色对应的site：

legend("topright",  # 图例位置可自行调整，比如"bottomleft"
       legend = levels(site_factor),
       pch = 21,
       pt.bg = site_colors,
       col = "black",
       bty = "n",  # 去掉图例边框
       title = "Site")

完整修改后的代码片段（整合到原有代码中） #

#running the db-RDA 
spe.rda.signif=capscale(species~canopy+gmpatch+site+year+Condition(pair), data=env, dist="bray")

#extract % explained by first 2 axes
perc <- round(100*(summary(spe.rda.signif)$cont$importance[2, 1:2]), 2)

#extract scores (coordinates in RDA space)
sc_si <- scores(spe.rda.signif, display="sites", choices=c(1,2), scaling=1)
sc_sp <- scores(spe.rda.signif, display="species", choices=c(1,2), scaling=1)
sc_bp <- scores(spe.rda.signif, display="bp", choices=c(1, 2), scaling=1)

#These are my location or site names that I want to use to define the colours of my points
site_names <- env$site

# 定义site对应的颜色
site_colors <- c("steelblue", "darkorange")
site_factor <- as.factor(site_names)

#set up blank plot with scaling, axes, and labels
plot(spe.rda.signif,
     scaling = 1, 
     type = "none", 
     frame = FALSE,
     xlim = c(-1,1),
     ylim = c(-1,1),
     main = "Triplot db-RDA - scaling 1",
     xlab = paste0("db-RDA1 (", perc[1], "%)"),
     ylab = paste0("db-RDA2 (", perc[2], "%)")
)

#add points for site scores - 按site分颜色
points(sc_si,
       pch = 21, 
       col = "black", 
       bg = site_colors[site_factor],
       cex = 1.2)

# 添加图例
legend("topright",
       legend = levels(site_factor),
       pch = 21,
       pt.bg = site_colors,
       col = "black",
       bty = "n",
       title = "Site")

# 继续添加物种名称和环境因子箭头（你的原有代码）
# text(sc_sp, labels = rownames(sc_sp), cex = 0.8)
# arrows(0, 0, sc_bp[,1], sc_bp[,2], length = 0.1, col = "red")

注意事项 #

• 如果site_names有超过2个类别，只需在site_colors中添加对应数量的颜色即可，顺序要和levels(site_factor)一致。
• 若不确定site_factor的levels顺序，可先运行levels(site_factor)查看，再调整site_colors的顺序。

内容的提问来源于stack exchange，提问作者LeahF